In 1966 Stilgoe played Benjamin in the West End musical, Jorrocks. He made his name on the BBC television teatime programme, Nationwide, followed by Esther Rantzen's That's Life!, a light-hearted consumer affairs programme for which he wrote comic songs satirising minor domestic misfortunes, often to the tune of "Oh! Mr Porter". One song was a satire on 'officials' who have, in the name of the song, Statutory Right of Entry to your Home; with Stilgoe playing and singing, in barber-shop style, all parts himself using trick photography. His ability to write a song from almost any source material and at speed is part of his cabaret act, which includes singing the instructions from a Swedish payphone; a pastiche of the King's Singers listing the kings and queens of England in which he sings all four parts; and composing a song in the interval from words and musical notes called out by the audience. He has also written and presented BBC radio programmes, including Hamburger Weekend, Used Notes, Stilgoe's Around, Maestro and Richard Stilgoe's Traffic Jam Show on BBC Radio 4.

In 1979, BBC aired "Decision '79 Breakfast Special" as part of its coverage of the parliamentary elections that brought Margaret Thatcher to power; the show featured Stilgoe singing the election results.[1] In 1981, Southern Television commissioned him to write a satirical song about the company that outbid them for southern England's ITV franchise, Television South; the result was "Portakabin TV," a reference to the portable buildings TVS was forced to use as studios and offices until its own purpose-built complex in Maidstone, Kent could be completed. The song was aired as part of Southern's final broadcast on 31 December 1981, a retrospective programme titled "And It's Goodbye From Us."[2]

In 1980 he wrote two Christmas songs, "Christmas Bells" and "Imitation Myrrh", which he sang with Broom Leys Junior School choir, from Coalville, Leicestershire. The songs were sold as a record at Christmas throughout Leicestershire to raise money for the Leicestershire Arts and Music Association. These two, with other Christmas pieces of his composition, also appeared in The Truth about Christmas – or Gold, Frankenstein and Merv – a one-off television programme in 1984, performed by Stilgoe and children from the Broom Leys Junior School Choir.

Stilgoe is a fan of anagrams and in 1980 he wrote the book The Richard Stilgoe Letters; a Jumble of Anagrams, using characters made of anagrams of his own name. These included Chris Dogtailer and Giscard O'Hitler. He has appeared over 200 times on the daytime TV quiz show, Countdown. Stilgoe also hosted quiz shows, including The Year in Question on Radio 4, Finders Keepers (1981–1985), and Scoop (1981–1982).[3] Stilgoe also wrote a 45-minute poem, "Who Pays the Piper?", which outlined the history of music from Pan to the modern day, interspersing classical music with re-written lyrics. He also appeared on a satirical BBC TV show of the 1980s, A Kick Up The Eighties.

Stilgoe wrote lyrics for Andrew Lloyd Webber's Starlight Express and collaborated with Charles Hart on the lyrics to The Phantom of the Opera. He also wrote two musicals for schools: Bodywork and Brilliant the Dinosaur. Stilgoe gave all his royalties as lyricist on Starlight Express to a village in India. Such was the musical's success that for some years his donations were exceeding £500 a day. He has appeared on the Royal Variety Performance and presented the Schools Proms for over 20 years, and has toured solo and with Peter Skellern.

In 1984, Stilgoe founded the Alchemy Foundation, which distributes money to good causes. The foundation is funded from Stilgoe's royalties from American productions of Starlight Express and The Phantom of the Opera.

Stilgoe founded the Orpheus Trust in 1998, in his former family home in Godstone, Surrey, offering performing arts experiences to young people with disabilities; he also started the Stilgoe Family Concerts series at the Royal Festival Hall, which feature young performers and regular commissions of new music.

He is patron of the Surrey Care Trust in Woking Surrey, which provides education, training, skills and volunteering opportunities to those who need motivation or a second chance in life. The charity also runs a fund to help those facing hardship throughout Surrey.